tjh.dev
Linux kernel mirror (for testing)
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linux
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Intel I/OAT DMA Linux driver
4 * Copyright(c) 2007 - 2009 Intel Corporation.
5 */
6
7#include <linux/kernel.h>
8#include <linux/pci.h>
9#include <linux/smp.h>
10#include <linux/interrupt.h>
11#include <linux/dca.h>
12
13#include <asm/cpuid/api.h>
14
15/* either a kernel change is needed, or we need something like this in kernel */
16#ifndef CONFIG_SMP
17#include <asm/smp.h>
18#undef cpu_physical_id
19#define cpu_physical_id(cpu) (cpuid_ebx(1) >> 24)
20#endif
21
22#include "dma.h"
23#include "registers.h"
24
25/*
26 * Bit 7 of a tag map entry is the "valid" bit, if it is set then bits 0:6
27 * contain the bit number of the APIC ID to map into the DCA tag. If the valid
28 * bit is not set, then the value must be 0 or 1 and defines the bit in the tag.
29 */
30#define DCA_TAG_MAP_VALID 0x80
31
32#define DCA3_TAG_MAP_BIT_TO_INV 0x80
33#define DCA3_TAG_MAP_BIT_TO_SEL 0x40
34#define DCA3_TAG_MAP_LITERAL_VAL 0x1
35
36#define DCA_TAG_MAP_MASK 0xDF
37
38/* expected tag map bytes for I/OAT ver.2 */
39#define DCA2_TAG_MAP_BYTE0 0x80
40#define DCA2_TAG_MAP_BYTE1 0x0
41#define DCA2_TAG_MAP_BYTE2 0x81
42#define DCA2_TAG_MAP_BYTE3 0x82
43#define DCA2_TAG_MAP_BYTE4 0x82
44
45/*
46 * "Legacy" DCA systems do not implement the DCA register set in the
47 * I/OAT device. Software needs direct support for their tag mappings.
48 */
49
50#define APICID_BIT(x) (DCA_TAG_MAP_VALID | (x))
51#define IOAT_TAG_MAP_LEN 8
52
53/* pack PCI B/D/F into a u16 */
54static inline u16 dcaid_from_pcidev(struct pci_dev *pci)
55{
56 return pci_dev_id(pci);
57}
58
59static int dca_enabled_in_bios(struct pci_dev *pdev)
60{
61 /* CPUID level 9 returns DCA configuration */
62 /* Bit 0 indicates DCA enabled by the BIOS */
63 u32 eax;
64 int res;
65
66 eax = cpuid_eax(CPUID_LEAF_DCA);
67 res = eax & BIT(0);
68 if (!res)
69 dev_dbg(&pdev->dev, "DCA is disabled in BIOS\n");
70
71 return res;
72}
73
74int system_has_dca_enabled(struct pci_dev *pdev)
75{
76 if (boot_cpu_has(X86_FEATURE_DCA))
77 return dca_enabled_in_bios(pdev);
78
79 dev_dbg(&pdev->dev, "boot cpu doesn't have X86_FEATURE_DCA\n");
80 return 0;
81}
82
83struct ioat_dca_slot {
84 struct pci_dev *pdev; /* requester device */
85 u16 rid; /* requester id, as used by IOAT */
86};
87
88#define IOAT_DCA_MAX_REQ 6
89#define IOAT3_DCA_MAX_REQ 2
90
91struct ioat_dca_priv {
92 void __iomem *iobase;
93 void __iomem *dca_base;
94 int max_requesters;
95 int requester_count;
96 u8 tag_map[IOAT_TAG_MAP_LEN];
97 struct ioat_dca_slot req_slots[];
98};
99
100static int ioat_dca_dev_managed(struct dca_provider *dca,
101 struct device *dev)
102{
103 struct ioat_dca_priv *ioatdca = dca_priv(dca);
104 struct pci_dev *pdev;
105 int i;
106
107 pdev = to_pci_dev(dev);
108 for (i = 0; i < ioatdca->max_requesters; i++) {
109 if (ioatdca->req_slots[i].pdev == pdev)
110 return 1;
111 }
112 return 0;
113}
114
115static int ioat_dca_add_requester(struct dca_provider *dca, struct device *dev)
116{
117 struct ioat_dca_priv *ioatdca = dca_priv(dca);
118 struct pci_dev *pdev;
119 int i;
120 u16 id;
121 u16 global_req_table;
122
123 /* This implementation only supports PCI-Express */
124 if (!dev_is_pci(dev))
125 return -ENODEV;
126 pdev = to_pci_dev(dev);
127 id = dcaid_from_pcidev(pdev);
128
129 if (ioatdca->requester_count == ioatdca->max_requesters)
130 return -ENODEV;
131
132 for (i = 0; i < ioatdca->max_requesters; i++) {
133 if (ioatdca->req_slots[i].pdev == NULL) {
134 /* found an empty slot */
135 ioatdca->requester_count++;
136 ioatdca->req_slots[i].pdev = pdev;
137 ioatdca->req_slots[i].rid = id;
138 global_req_table =
139 readw(ioatdca->dca_base + IOAT3_DCA_GREQID_OFFSET);
140 writel(id | IOAT_DCA_GREQID_VALID,
141 ioatdca->iobase + global_req_table + (i * 4));
142 return i;
143 }
144 }
145 /* Error, ioatdma->requester_count is out of whack */
146 return -EFAULT;
147}
148
149static int ioat_dca_remove_requester(struct dca_provider *dca,
150 struct device *dev)
151{
152 struct ioat_dca_priv *ioatdca = dca_priv(dca);
153 struct pci_dev *pdev;
154 int i;
155 u16 global_req_table;
156
157 /* This implementation only supports PCI-Express */
158 if (!dev_is_pci(dev))
159 return -ENODEV;
160 pdev = to_pci_dev(dev);
161
162 for (i = 0; i < ioatdca->max_requesters; i++) {
163 if (ioatdca->req_slots[i].pdev == pdev) {
164 global_req_table =
165 readw(ioatdca->dca_base + IOAT3_DCA_GREQID_OFFSET);
166 writel(0, ioatdca->iobase + global_req_table + (i * 4));
167 ioatdca->req_slots[i].pdev = NULL;
168 ioatdca->req_slots[i].rid = 0;
169 ioatdca->requester_count--;
170 return i;
171 }
172 }
173 return -ENODEV;
174}
175
176static u8 ioat_dca_get_tag(struct dca_provider *dca,
177 struct device *dev,
178 int cpu)
179{
180 u8 tag;
181
182 struct ioat_dca_priv *ioatdca = dca_priv(dca);
183 int i, apic_id, bit, value;
184 u8 entry;
185
186 tag = 0;
187 apic_id = cpu_physical_id(cpu);
188
189 for (i = 0; i < IOAT_TAG_MAP_LEN; i++) {
190 entry = ioatdca->tag_map[i];
191 if (entry & DCA3_TAG_MAP_BIT_TO_SEL) {
192 bit = entry &
193 ~(DCA3_TAG_MAP_BIT_TO_SEL | DCA3_TAG_MAP_BIT_TO_INV);
194 value = (apic_id & (1 << bit)) ? 1 : 0;
195 } else if (entry & DCA3_TAG_MAP_BIT_TO_INV) {
196 bit = entry & ~DCA3_TAG_MAP_BIT_TO_INV;
197 value = (apic_id & (1 << bit)) ? 0 : 1;
198 } else {
199 value = (entry & DCA3_TAG_MAP_LITERAL_VAL) ? 1 : 0;
200 }
201 tag |= (value << i);
202 }
203
204 return tag;
205}
206
207static const struct dca_ops ioat_dca_ops = {
208 .add_requester = ioat_dca_add_requester,
209 .remove_requester = ioat_dca_remove_requester,
210 .get_tag = ioat_dca_get_tag,
211 .dev_managed = ioat_dca_dev_managed,
212};
213
214static int ioat_dca_count_dca_slots(void *iobase, u16 dca_offset)
215{
216 int slots = 0;
217 u32 req;
218 u16 global_req_table;
219
220 global_req_table = readw(iobase + dca_offset + IOAT3_DCA_GREQID_OFFSET);
221 if (global_req_table == 0)
222 return 0;
223
224 do {
225 req = readl(iobase + global_req_table + (slots * sizeof(u32)));
226 slots++;
227 } while ((req & IOAT_DCA_GREQID_LASTID) == 0);
228
229 return slots;
230}
231
232static inline int dca3_tag_map_invalid(u8 *tag_map)
233{
234 /*
235 * If the tag map is not programmed by the BIOS the default is:
236 * 0x80 0x80 0x80 0x80 0x80 0x00 0x00 0x00
237 *
238 * This an invalid map and will result in only 2 possible tags
239 * 0x1F and 0x00. 0x00 is an invalid DCA tag so we know that
240 * this entire definition is invalid.
241 */
242 return ((tag_map[0] == DCA_TAG_MAP_VALID) &&
243 (tag_map[1] == DCA_TAG_MAP_VALID) &&
244 (tag_map[2] == DCA_TAG_MAP_VALID) &&
245 (tag_map[3] == DCA_TAG_MAP_VALID) &&
246 (tag_map[4] == DCA_TAG_MAP_VALID));
247}
248
249struct dca_provider *ioat_dca_init(struct pci_dev *pdev, void __iomem *iobase)
250{
251 struct dca_provider *dca;
252 struct ioat_dca_priv *ioatdca;
253 int slots;
254 int i;
255 int err;
256 u16 dca_offset;
257 u16 csi_fsb_control;
258 u16 pcie_control;
259 u8 bit;
260
261 union {
262 u64 full;
263 struct {
264 u32 low;
265 u32 high;
266 };
267 } tag_map;
268
269 if (!system_has_dca_enabled(pdev))
270 return NULL;
271
272 dca_offset = readw(iobase + IOAT_DCAOFFSET_OFFSET);
273 if (dca_offset == 0)
274 return NULL;
275
276 slots = ioat_dca_count_dca_slots(iobase, dca_offset);
277 if (slots == 0)
278 return NULL;
279
280 dca = alloc_dca_provider(&ioat_dca_ops,
281 struct_size(ioatdca, req_slots, slots));
282 if (!dca)
283 return NULL;
284
285 ioatdca = dca_priv(dca);
286 ioatdca->iobase = iobase;
287 ioatdca->dca_base = iobase + dca_offset;
288 ioatdca->max_requesters = slots;
289
290 /* some bios might not know to turn these on */
291 csi_fsb_control = readw(ioatdca->dca_base + IOAT3_CSI_CONTROL_OFFSET);
292 if ((csi_fsb_control & IOAT3_CSI_CONTROL_PREFETCH) == 0) {
293 csi_fsb_control |= IOAT3_CSI_CONTROL_PREFETCH;
294 writew(csi_fsb_control,
295 ioatdca->dca_base + IOAT3_CSI_CONTROL_OFFSET);
296 }
297 pcie_control = readw(ioatdca->dca_base + IOAT3_PCI_CONTROL_OFFSET);
298 if ((pcie_control & IOAT3_PCI_CONTROL_MEMWR) == 0) {
299 pcie_control |= IOAT3_PCI_CONTROL_MEMWR;
300 writew(pcie_control,
301 ioatdca->dca_base + IOAT3_PCI_CONTROL_OFFSET);
302 }
303
304
305 /* TODO version, compatibility and configuration checks */
306
307 /* copy out the APIC to DCA tag map */
308 tag_map.low =
309 readl(ioatdca->dca_base + IOAT3_APICID_TAG_MAP_OFFSET_LOW);
310 tag_map.high =
311 readl(ioatdca->dca_base + IOAT3_APICID_TAG_MAP_OFFSET_HIGH);
312 for (i = 0; i < 8; i++) {
313 bit = tag_map.full >> (8 * i);
314 ioatdca->tag_map[i] = bit & DCA_TAG_MAP_MASK;
315 }
316
317 if (dca3_tag_map_invalid(ioatdca->tag_map)) {
318 add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
319 pr_warn_once("%s %s: APICID_TAG_MAP set incorrectly by BIOS, disabling DCA\n",
320 dev_driver_string(&pdev->dev),
321 dev_name(&pdev->dev));
322 free_dca_provider(dca);
323 return NULL;
324 }
325
326 err = register_dca_provider(dca, &pdev->dev);
327 if (err) {
328 free_dca_provider(dca);
329 return NULL;
330 }
331
332 return dca;
333}